The Washington Post reports that supporters of comprehensive immigration reform within the Republican Party are waging “a behind-the-scenes campaign to discredit the influential advocacy groups” that oppose such reform. The advocacy groups under attack are Numbers USA, the Center for Immigration Studies (CIS), and Federation for American Immigration Reform (FAIR). They stand accused of being driven by an agenda of population control that includes support of abortion and sterilization.

This is malicious nonsense. With respect to Numbers USA and FAIR, its critics cite reports “that warn of environmental devastation from unchecked population growth.” But no evidence is presented that either group favors abortion or sterilization. Many on both sides of the abortion debate can probably agree that “unchecked population growth” is undesirable.

As for CIS, critics point to a 1993 research paper sympathetic to contraception and the RU-486 abortion pill. The fact that the critics are relying on one 20 year-old “research paper” demonstrates the weakness and irresponsibility of their position.

Perhaps the most disturbing element of the Post’s story is its account of Marco Rubio’s role in the smear campaign. According to the Post, Rubio’s aides brought “strategist” Mario Lopez to a meeting of GOP Senate staffers so that Lopez could distribute literature attacking Numbers USA, CIS, and FAIR. Lopez is the author of an article accusing these groups of “hijacking” the immigration debate for their own purposes.

In addition, a Rubio spokesman, Alex Conant, attributes to his boss the view that “some groups that oppose legal immigration should not be considered part of the conservative movement.” I support “legal immigration,” at least until Chuck Schumer, Lindsey Graham, John McCain, and Rubio redefine it. But I don’t believe Rubio should be reading those who disagree with him out of the conservative movement. Nor should Rubio be trying to tilt the debate in his favor by sponsoring smear campaigns against those who disagree with his position on illegal immigration.

Lately, I have been worrying that the long-term effect of Rubio’s vision of comprehensive immigration might well be to split the Republican Party in two, leaving us with three parties: (1) a progressive party, (2) a pandering “Republican” party that hopes (against hope) to compete for votes from the “center” of a much more left-leaning electorate, and (3) a “paleo/libertarian” that insists on a more conservative vision. The leaders of the three parties might resemble the three SOTU speakers from Tuesday — Barack Obama, Marco Rubio, and Rand Paul — with the Rubio and Paul figures shifting their emphasis somewhat.